All one arm at a time: Bent over rows, Hi-pulls, cleans, side presses and shoulder presses/jerks. All power & mass builders. Usually the free arm is bracing it's self onto a near by support, some times not. Surprising news, for some, that the bench or inclines are not the only exercises one can do with heavy DB's.
One legged step-up's, Romanian squats or regular squats and SLDL's (both hands or one hand at a time...suggest trying the one hands version, for a little variety in the workout). One arm at a time can give some insurance of equal strength, muscle development and balance with each side of the body to the other. that goes for any upper body movement also.
